hello. i have been tested 4 times since i've been sexually active (over 3 years now) and have never got an STD. i have been with my current partner for 3 years. we use birth control and not condoms. I slept with one other person without a condom. i then got checked for STDs and came back negative. Is it posible for me to transfer an STD from one male partner to another, and I have no symptoms? Are there certain diseases for men that don't have symptoms in females?